FAST TRACK MATRIX METALLOPROTEINASE-19 IS EXPRESSED BY PROLIFERATING EPITHELIUM BUT DISAPPEARS WITH NEOPLASTIC DEDIFFERENTIATION Ulla IMPOLA 1 , Mervi TORISEVA 2–4 , Sari SUOMELA 1 , Leila JESKANEN 1,5 , Niina HIETA 2–4 , Tiina JAHKOLA 6 , Reidar GRENMAN 7 , Veli-Matti K¨ AH ¨ ARI 2–4 and Ulpu SAARIALHO-KERE 1 * 1 Department of Dermatology, Helsinki University Central Hospital and Biomedicum Helsinki, Helsinki, Finland 2 Department of Dermatology, Turku University Central Hospital, Turku, Finland 3 Department of Medical Biochemistry, University of Turku, Turku, Finland 4 Turku Center for Biotechnology, Åbo Akademi University, Turku, Finland 5 Department of Pathology, Helsinki University Central Hospital and Biomedicum Helsinki, Helsinki, Finland 6 Department of Plastic Surgery, Helsinki University Central Hospital, Helsinki, Finland 7 Department of Otorhinolaryngology–Head-and-Neck Surgery, Turku University Central Hospital, Turku, Finland MMP-19 (also designated RASI) is a recently discovered member of a large family of zinc-dependent proteolytic en- zymes, most of which have been implicated in cancer growth and metastasis. It differs from the others by its chromosomal location and structure and is expressed by endothelial and vascular smooth muscle cells in vivo. Our aim was to study the putative role of MMP-19 in skin cancer. We also exam- ined its regulation in keratinocyte cultures using quantitative TaqMan RT-PCR. Our results show that MMP-19 can also be detected in stimulated keratinocytes by Northern and West- ern analyses. In wounds, it was found in keratinocytes outside the migrating area, while in BCC and SCC, it was present in the hyperproliferative (p63-positive), E-cadherin-negative epidermis at the tumor surface but downregulated in inva- sive cancer islands. Expression was also evident in endothelial cells of neoangiogenic regions and in occasional stromal fi- broblasts. Of the 12 tested cytokines/growth factors, only TNF- and PMA were able to stimulate the expression of MMP-19 mRNA in primary keratinocytes. No MMP-19 mRNA was detected by Northern analysis in cultured HaCaT or A5 cells or in an SCC cell line established from head-and- neck cancer. Our data suggest that, unlike most MMPs, MMP-19 expression in the epidermis is downregulated during transformation and histologic dedifferentiation. © 2002 Wiley-Liss, Inc. Key words: skin cancer; keratinocyte; wound healing; tumor necrosis factor- MMPs constitute a family of zinc-dependent proteolytic en- zymes which take part in proteolytic degradation of the ECM and BM during cell migration, angiogenesis and proteolytic activation of growth factors, events that are needed in normal tissue remod- eling as well as in wound healing and tumor invasion. MMPs can be divided into 6 subgroups: interstitial collagenases (MMP-1, MMP-8 and MMP-13), stromelysins (MMP-3, MMP-10, MMP-11 and MMP-12), matrilysins (MMP-7 and MMP-26), type IV col- lagenases (MMP-2 and MMP-9), membrane-type MMPs (MMP- 14, MMP-15, MMP-16, MMP-17, MMP-24 and MMP-25) and others (MMP-19, MMP-23 and MMP-28). 1–3 Collagenase-1 (MMP-1), stromelysin-2 (MMP-10) and 92 kDa gelatinase (MMP-9) participate in keratinocyte migration during wound re- pair as well as in cancer cell migration. 4,5 The role of the novel MMPs (from MMP-19 upward) in skin biology has not been well elucidated. MMP-19, previously referred to as MMP-18, 6 is one of the recently cloned members of the MMP family. It differs from the others by its unique chromosomal location (12q14). 7 MMP-19 lacks several structural features known to be present in other MMP subclasses, including Asp, Tyr and Gly residues close to the zinc-binding site; the fibronectin-like and the transmembrane do- mains; as well as the furin-activation sequence, based on which it cannot be included into any of the known subclasses. 7 Another recently cloned MMP, epilysin (MMP-28), is structurally most related to MMP-19. 3,8 In vitro, MMP-19 is able to degrade many important BM components, e.g., type IV collagen, laminin-1, nidogen, fibronectin, tenascin-C isoform, aggrecan, type I gelatin and cartilage oligomeric matrix protein, 9 but does not activate any other latent MMPs. 10 By Northern hybridization, MMP-19 was originally detected in placenta, lung, pancreas, liver, ovary, spleen and intestine. 7 Inde- pendently, it was isolated as an autoantigen from the inflamed synovium of a patient suffering from rheumatoid arthritis. 11 MMP-19 has been described in smooth muscle cells of the tunica media of large blood vessels, normal skin and uterine ligaments as well as in endothelial cells of acutely inflamed synovial capillar- ies. 12 It is also detected on the surface of activated peripheral blood mononuclear cells, TH1 lymphocytes and Jurkat T-lymphoma cells. 11 MMP-19 has been suggested to play a role in matrix remodeling and in the pathogenesis of rheumatoid arthritis. 11,13 Because of its appearance in normal tissues, it is possible that MMP-19 is important in normal tissue remodeling or activation of secreted and membrane-bound proteins, like growth factors. 10 Our aim was to determine whether MMP-19 is induced in the epithelium during remodeling associated with either wound repair or cancer invasion. We show here that MMP-19 can be expressed by proliferating, but not migrating, keratinocytes; is upregulated Abbreviations: AP-1, activator protein-1; BCC, basal cell cancer; bFGF, basic fibroblast growth factor; BM, basement membrane; BPE, bovine pituitary extract; ECL, enhanced chemiluminescence; ECM, extracellular matrix; EGF, epidermal growth factor; GAPDH, glyceraldehyde-3-phos- phate dehydrogenase; HGF, hepatocyte growth factor; KGM, keratinocyte growth medium; MAb, monoclonal antibody; MMP, matrix metallopro- teinase; PEA3, phenylethylamine-3; PMA, phorbol myristate acetate; SCC, squamous cell cancer; TGF-, transforming growth factor-; TNF-,  tumor necrosis factor-; TPA, tissue plasminogen activator; VEGF, vas- cular endothelial growth factor. Grant sponsor: Helsinki and Turku University Central Hospital Research Funds; Grant sponsor: Academy of Finland; Grant sponsor: Finska L¨ akares¨ allskapet; Grant sponsor: Sigrid Jus´ elius Foundation; Grant spon- sor: Cancer Foundation of Finland. *Correspondence to: Department of Dermatology, Helsinki University Central Hospital, Meilahdentie 2, 00250 Helsinki, Finland. Fax: +358-9-4718-6561. E-mail: ulpu.saarialho-kere@helsinki.fi Received 17 May 2002; Revised 27 September 2002; Accepted 18 October 2002 DOI 10.1002/ijc.10902 Int. J. Cancer: 103, 709 –716 (2003) © 2002 Wiley-Liss, Inc. Publication of the International Union Against Cancer